Aircraft noise continues to be a nuisance. Increases in air traffic and growth in populations that surround airports are resulting in a noise impact on a larger percentage of the community and a stronger desire to reduce the noise around airports. Commercial technology necessary to significantly reduce the footprint is not yet available and may be 20 years away. In response to this, NASA is working to develop the required technologies. The goal of this Advanced Subsonic Technology program is to develop high-payoff technologies that enable a safe, highly productive global air transportation system. This system will include a new generation of aircraft and engines that are both environmentally compatible and economical.